1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to radio frequency identification (RFID) communication systems including RFID readers that communicate with RFID tags.
2. Background Art
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored wirelessly by devices known as “readers.” Readers typically have one or more antennas transmitting radio frequency signals to which tags respond. Since the reader “interrogates” RFID tags, and receives signals back from the tags in response to the interrogation, the reader is sometimes termed as “reader interrogator” or simply “interrogator”.
In a RFID system, typically a reader transmits a continuous wave (CW) or modulated radio frequency (RF) signal to a tag. The tag receives the signal, and responds by modulating the signal, “backscattering” an information signal to the reader. The reader receives signals back from the tag, and the signals are demodulated, decoded and further processed.
With the maturation of RFID technology, efficient communications between tags and readers has become a key enabler in supply chain management, especially in manufacturing, shipping, and retail industries, as well as in building security installations, healthcare facilities, libraries, airports, warehouses etc.
RFID readers tend to be expensive, and may be required to be set up in numerous areas to provide necessary coverage of tags. Thus, in a given facility, a large number of readers may be needed to be purchased to provide full coverage. What is needed are ways of providing RFID reader coverage to all desired areas of RFID enabled facilities, while reducing overall RFID system costs.